Historically, the most widely used approach for installing a roof bolt in the roof or side wall of a mine included the use of an expandable nut on the end of the bolt to engage the side wall of the bore hole and hold the bolt in place. With the development of strong epoxy resins, mine operators began to use a resin cartridge in the distal end of the bore hole to provide additional holding force. As the roof bolt is pushed in the drilled hole and rotated during the installation process, the resin cartridge is ruptured and the catalyst mixes with the epoxy resin to form a hardened, permanent adhesive mass around the expandable nut and the adjacent bolt surface and anchoring against the inside surface of the hole.
In more recent years, as the epoxy resins have been further developed to make them stronger and provide for more rapid hardening, some roof bolt designs have eliminated the expandable nut on the end. Indeed, one of the most popular roof bolts today comprises simply a common reinforcing bar or rebar. The distal end of the rebar engages the resin cartridge in the distal end of the bore hole. As the proximate end of the rebar is engaged and rotated by a socket driven by a spinner, the cartridge ruptures mixing the catalyst with the resin. The mixture rapidly hardens to secure the roof bolt in place.
One area of continuing development with relation to the roof bolting method is the step of insertion of the resin cartridge into the bore hole. Originally, the operator of the roof bolting equipment worked from the mine floor inserting the resin cartridge into the bore hole by hand. In a relatively narrow coal seam mine, where the roof is low, this works reasonably well. However, as the seam thickness increases, and the roof moves up to the eight plus foot mark, the efficiency of the operation falls dramatically. In most instances a ladder is required, which means the process is slower, and much more physically demanding.
In attempts to alleviate these problems, inventors began to employ a hollow tube into which the resin cartridge was loaded; the tube being mounted with the drill on a turret, or on a similar carrier with a hydraulic lift. The cartridge is usually blown into the bore hole from the tube by water or air.
Development of the cartridge insertion technology within the last decade continues to focus on the use of different methods of using the pressurized fluid to drive the cartridge through a tube and into the bore hole. As far as we are aware, the tube is always mounted on a turret or the like supported by the roof bolter machine. For example, the Issakainen et al. U.S. Pat. No. 4,576,525 provides a side-by-side drill/tube, with the resin cartridge being inserted into the bore hole by pressurized fluid. In this apparatus, water is the preferred pressurized fluid that is used. However, the inventors recognize the need for additional driving force, as well as holding power, so that in addition they employ a separate slug of cement behind the cartridge after being inserted by the water injection step. A similar approach is taken in the patent to Wallin, U.S. Pat. No. 5,165,825. The advance in technology attempted in this later patent is to improve the mounting of the drill, the water injection tube, and the bolter on the turret. As will be realized, the proported advance in this machine is to further automate the procedure, but in reality the system is truly characterized by simply further complicating it. The expense of the water operated system, and the inherent mess that it causes is simply aggravated. The need for protective clothing for the operator appears to have been increased, thus leading to substantial discomfort for the operator. The maintenance and the fluid/material supply costs are greater. Due to need for multiple movements of the turret and its supporting boom, the power consumption is considerably increased.
Other approaches with regard to the common fluid injection systems for the resin cartridge simply offer the substitution of pressurized air for the water. Over the last decade these systems have also maintained their complicated and expensive nature, along with the increased expense of operation due to the need for large volumes of compressed air. For example, the Combet U.S. Pat. No. 4,588,037 provides such a system for turret mounting of the drill and the pneumatic injection of the resin cartridge.
The Morrison et al. U.S. Pat. No. 5,494,380 even further complicates the system by combining air and water in an attempt to provide more efficient resin cartridge delivery into the bore hole. The bottom line is that over time, and especially over the last decade, the prevailing consideration in the field is to provide more and more complicated and expensive fluid pressure systems in mostly failed experiments to improve the basic roof bolting method that uses epoxy resin for anchoring the roof bolt.
With the above trend toward complicating the method for installing roof bolts, and in particular the roof bolting method that uses epoxy resin to anchor the roof bolt, a need is now recognized for utilizing a different approach. Specifically, what we now envision as needed is a system of roof bolting, including inserting the resin cartridge into the bore hole, so as to uncomplicate the procedure. We especially see a need for reversing the escalating cost of the machines that heretofore focus on utilizing expensive turrets or the like, and wasteful pressurized fluid to push the cartridge into the bore hole. An approach is needed that is not only simpler, but more efficient for the operator of the roof bolter machine to use.
Accordingly, it is a primary object of the present invention to provide an improved in-situ roof/side wall bolting system, and related method/apparatus, where there is a departure from the prior art shortcomings of progressively complicated and more expensive, higher maintenance and operating cost attachments for the roof bolter machine.
It is another object of the present invention to provide a simplified and more efficient bolting system, method and related apparatus, wherein the resin cartridge for anchoring the roof bolt is mechanically pushed into the bore hole through a hollow, elongated wand that is manually operated.
It is still another object of the present invention to provide a simplified method/apparatus for a roof bolting system wherein the resin cartridge is manually loaded into the delivery end of a light weight wand that is capable of free and easy handling by the operator of the machine; the wand being manually placed in position adjacent the mouth of the bore hole and the cartridge mechanically pushed to the end in a reliable manner, and without the use of fluid being blown into the bore hole.
It is still another object of the present invention to provide a bolting system/method/apparatus and related resin cartridge insertion procedure, wherein a flexible, spring snake assembly with a driver, is mounted on a roof bolt machine to be utilized to push the resin cartridge through a manually manipulated hollow wand and into the bore hole for efficient and reliable positioning in the end of the bore hole to anchor the roof bolt.
Yet another object of the present invention is to provide such a roof bolting and resin cartridge insertion system that does not need a supply of fluid, either water or air, and provides improved and more efficient insertion of the resin cartridge into the bore hole for anchoring the roof bolt.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described, an improved method and related apparatus for installation of roof bolts in the roof or side wall of a mine comprises the steps of first drilling a bore hole, loading a resin cartridge in a hand held tubular wand, manually placing the wand with the delivery end adjacent the entrance orifice or mouth of the bore hole and pushing the cartridge through the wand for inserting it into the bore hole. Once the cartridge is in position in the bore hole, the roof bolt is placed in position and the resin cartridge is mixed by spinning the bolt. This action is operative to set the bolt securely in the rock. Utilizing this method, a simplified and more efficient operation for supporting the roof or side wall is possible. With this apparatus the operator's effective reach for manually inserting the resin cartridge in the bore hole is extended, minimizing the need for repositioning and thus allowing the operator to remain in the protected operator area. The complicated mechanical turrets that have dominated the operation in recent years, and the initial expense and attendant increased operating costs and maintenance is advantageously eliminated.
According to another feature of the present invention, the method can be most beneficially used with a roof bolting machine having an elevating boom that includes a drill head with a spinner and a drill guide; the guide being mounted at the forward end of the boom. According to the present invention, as the wand is manually placed in position for transfer of the resin cartridge into the bore hole, the end of the wand rests on the boom adjacent the drill guide. This provides the operator with assistance in the smooth and efficient transfer of the cartridge into the bore hole.
The best approach for loading the resin cartridge into the wand is performed simply by dropping the cartridge into the delivery end of the wand. The wand can be held in brackets, or supported by the operator during this step. This eliminates the need for opening and closing a side loading access into the wand and further simplifies the method and related apparatus.
To provide the movement of a cartridge without the use of either water or air pressure, an extensible flexible spring snake assembly is used. A driver, preferably in the form of a rotating reel, moves the spring axially along the wand behind the cartridge and into the bore hole. The spring for pushing the cartridge within the snake assembly is housed in a flexible sheath and includes a cylindrical head on the operative end that has a diameter substantially matching the inside of the wand and the bore hole. The head provides for a more efficient movement of the resin cartridge along its path through the wand and into the bore hole.
The wand with the snake assembly is light weight, and it includes a handle at its proximate end so that it can be easily manipulated and positioned by the operator. A retainer is positioned behind the cartridge in order to protect the cartridge from premature rupture as it is engaged by the head on the spring of the snake assembly. The retainer has trailing prongs providing a one-way stop as it moves into the hole, thus preventing retro-movement of the cartridge once it is in place.
The related apparatus for use with the roof bolting machine includes the tubular wand that is manually loaded and placed with the delivery end adjacent the mouth/entrance orifice of the bore hole. The wand incorporates a flexible pusher, that is extensible through the wand and into the hole for transfer of the cartridge into the bore hole. A driver is mounted on the roof bolting machine and provides the motive force in order to move the pusher, as required. Preferably, the pusher comprises a spring in a sheath and a cylindrical head on the end of the spring for engagement with the cartridge. A handle on the proximate end of the tubular wand adjacent the connection with the pusher facilitates the manual manipulation of the wand. As a consequence, a simplified and more efficient operation for insertion of the resin cartridge in the bore hole for the roof bolting method of the present invention is provided.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.